Dmg/heal Recount Script ?

Can Dmg Recount and Healing recount be implemented in scripts ? (Something similar like addons but in script)
If a healer heals a target with full hp does that heal still counting on recount?

If I add some code in the On_Enter_world Hook inside the core (after i compile the core) does that code executes when i Register the event hook or it just executes only what is in the function description?

Addons are scripts too, just client side scripts ( they are compiled and executed by the client, wow.exe ), not server side.
When you register a script it runs every time the event you registered for happens.

Either way, I highly doubt you could make a server side recount script at this point.